The effects of cable capacitance on longwall power systems.
Novak T; Basar J; Sottile J; Kohler JL
Proceedings of the 38th IEEE Industry Applications Society Annual Meeting. Vol. 3. Los Angeles, CA: IEEE Industry Applications Society, 2003 Oct; :1615-1621
Utilization voltages used on longwall equipment operating in U.S. coal mines have increased steadily over the past 15 years from 1,000 V to 4,160 V. This voltage increase has directly influenced the 200% gain in overall longwall productivity from 1987 to the present. The transition from medium voltage (661 V-1,000 V) to high voltage (>1,000 V) has permitted significant increases in face widths and equipment sizes. Longwall systems with total connected loads of over 5,000 hp are now common, and all U.S. longwalls now use high-voltage equipment, with most using 4,160 V. Shielded cables, which have significantly more capacitance than unshielded cables, are required for high-voltage applications in the mining industry. This capacitance can have detrimental influences on system overvoltages and relay selectivity during ground-fault conditions if the values for the grounding resistor and the ground-fault-relay pickup settings are improperly chosen. These issues are addressed in this paper.
Longwall-mining; Mining-equipment; Coal-mining; Electrical-systems; Electricity
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Proceedings of the 38th IEEE Industry Applications Society Annual Meeting